Spectral analysis of RE3+ (RE = Sm, Dy, and Tm): P2O5–Al2O3–Na2O glasses

Phosphate glasses in the compositions of 70P2O5–15Al2O3–14Na2O–1RE3+ (RE = Sm, Dy, and Tm) (mol%) were prepared by melt-quenching technique and characterized optically. The differential thermal analysis (DTA) profile of the host glass was carried out to confirm its thermal stability. For all the glasses absorption, photoluminescence and decay measurements have also been carried out. These glasses have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω2, Ω4 and Ω6) have been calculated for all the studied ions. For Sm3+ doped glass, four emission bands centered at 562 nm (4G5/2 → 6H5/2), 598 nm (4G5/2 → 6H7/2), 644 nm (4G5/2 → 6H9/2), and 704 nm (4G5/2 → 6H11/2) have been observed with 402 nm (6H5/2 → 4F7/2) excitation wavelength. Of them, 598 nm (4G5/2 → 6H7/2) has shown a bright orange emission. With regard to Dy3+ doped glass, a blue emission band centered at 486 nm (4F9/2 → 6H15/2) and a bright yellow emission at 575 nm (4F9/2 → 6H13/2) have been observed, apart from 662 nm (4F9/2 → 6H11/2) emission transition with an excitation at 388 nm (6H15/2 → 4I13/2,4F7/2) wavelength. Emission bands of 650 nm (1G4 → 3F4) and 785 nm (1G4 → 3H5) transitions for the Tm3+ doped glass, with an excitation wavelength at 466 nm (3H6 → 1G4), have also been observed. The stimulated emission cross-sections of all the emission bands of RE3+ glasses (RE = Sm, Dy, and Tm) have been computed based on their measured full-width at half maximum (FWHM, Δλ) and measured lifetimes (τm).